Thixotropic overbased calcium sulfonate complex thickened compositions having corrosion-inhibiting properties, and having utility, as such, or as ingredients of corrosion-inhibiting compositions, for a variety of uses such as, for instance, in automobile and truck body undercoatings, and for numerous other purposes, are known to the art and are disclosed in various publications and patents, illustrative of which are U.S. Pat. Nos. 3,242,079; 3,372,115; 3,376,222; 3,377,283; 3,523,898; 3,661,622; 3,671,012; 3,746,643; 3,730,895; 3,816,310; 3,492,231; 4,597,880; and Canadian Pat. No. 949,055. Such thickened compositions have gone into widespread use either as such, or, more commonly, admixed with other ingredients to produce compositions for use in a variety of environments, and, generally speaking, they are characterized by reasonably good E. P. and antiwear properties, high dropping points, reasonably good resistance to mechanical breakdown, salt spray and water-corrosion resistance, thermal stability at high temperatures, and other desirable properties, as described in the aforesaid patents. Such heretofore known thickened compositions are conventionally commercially prepared by what is known as a 2-step process, as more particularly shown in the aforesaid U.S. Pat. Nos. 3,242,079; 3,372,115; and 3,492,231. They have also been commercially prepared by what is known as a 1-step process, as noted above, and as is shown, for instance, in the aforementioned U.S. Pat. Nos. 3,761,012; 3,746,643; 3,816,310; 4,597,880; and Canadian Pat. No. 949,055 which also discloses heretofore known 2-step processes. The aforementioned U.S. Pat. No. 4,597,880 describes and identifies numbers of known 2-step processes and sets out the nature thereof and acknowledges the previously recognized delineations between 2-step processes and 1-step processes. Our present invention, as indicated above, is directed to the art dealing with 1-step processes and is concerned with a novel 1-step process which is characterized by marked and significant improvements and advantages over what, in our consideration, is, overall, the best of the heretofore known 1-step processes of which we are aware, namely, that of the aforementioned U.S. Pat. No. 4,597,880, for the preparation of thixotropic overbased calcium sulfonate complexes in the form of thickened compositions, generally in the form of greases.
U.S. Pat. No. 3,746,643 discloses a 1-step process of preparing thixotropic overbased calcium sulfonate complex thickened rust-inhibiting compositions wherein small amounts of water and an alcohol are incorporated into a mixture of a nonvolatile diluent oil, a calcium carbonate complex, and an oil-soluble calcium sulfonate dispersing agent. In said mixture, the calcium sulfonate dispersing agent is stated to range from about 2 to about 65 wt. %; the nonvolatile diluent oil is stated to range from about 5 to about 80 wt. %; the calcium carbonate complex is stated to range from about 1 to about 25 wt. %; and the water and alcohol are stated to range from about 1 to about 6 wt. %, and from about 1 to about 40 wt. %, respectively. In addition, the mixture of said ingredients is stated to include, optionally, up to 60 wt. % of a volatile processing solvent. The resulting mixture of ingredients is then stated to be heated under controlled conditions to convert the mixture to a rust-inhibiting composition (when cut back with a light hydrocarbon solvent). This patent points out that, to obtain the desired products, the mixture must be heated to a temperature exceeding 50.degree. C. (122.degree. F.), and that it is necessary in traversing the temperature zone from about 50.degree. C. to about 100.degree. C. (212.degree. F.) that the rate of temperature increase not exceed a certain maximum limit where the amount of water present in the mixture is less than 2.5 moles of water per mole of calcium metal present as the carbonate complex.
U.S. Pat. No. 3,671,012 discloses a 1-step process of preparing thixotropic overbased calcium sulfonate complex thickened compositions. This is disclosed more particularly in column 6, lines 40 to the bottom of the page, extending through columns 7 and 8 and through line 25 in column 9. The procedure described in U.S. Pat. No. 3,671,012 is generally similar to that shown in U.S. Pat. No. 3,746,643, except that the disclosure in U.S. Pat. No. 3,671,012 is in somewhat greater detail than is described in U.S. Pat. No. 3,746,643.
U.S. Pat. No. 4,597,880 discloses a 1-step process to prepare thixotropic overbased calcium sulfonate thickened compositions whereby a sulfonic acid, Ca(OH).sub.2, alkanol, water and a water-soluble carboxylic acid, preferably acetic acid, are carbonated with 0.8 to 1 mole CO.sub.2 /mole lime within a temperature range of 95.degree. to 200.degree. F. until the reaction mixture is changed to a thickened composition.
U.S. Pat. No. 3,816,310 is, in numbers of respects and speaking generally, similar in its disclosure of known 1-step processes to the 1-step process disclosed in the above referred to U.S. Pat. Nos. 3,746,643 and 3,671,012 for the preparation of thixotropic overbased calcium sulfonate complex thickened compositions. Taking as illustrative the 1-step process as described in U.S. Pat. No. 3,816,310, as there described in a typical or illustrative embodiment, an admixture is formed comprising essentially an oil-soluble sulfonic acid (or a preformed oil-soluble calcium sulfonate dispersing agent prepared from said oil-soluble sulfonic acid), said sulfonic acid being preferably linear or branched chain "NAB" Bottoms or C.sub.15 -C.sub.18 linear alkylbenzene sulfonic acids; liquid medium or carrier material, for instance, a mineral oil; a C.sub.1 -C.sub.3 alkanol, for instance, methyl alcohol; calcium oxide and/or calcium hydroxide; and water; then carbonating the resulting admixture with carbon dioxide, while maintaining the temperature below about 165.degree. F., to the extent that at least 1.5 moles of the carbon dioxide per mole of the calcium carbonate are present in the mixture; and then heating the carbonated admixture to a temperature above 212.degree. F., said heating step being characterized in that the time required to heat to 212.degree. F. is from about 0.5 to about 8 hours, the process being characterized further in that, alternatively, the water which is utilized is initially added to the other ingredients to be reacted, or, depending on certain circumstances, may be added after the carbonation step or just prior to the heating step after carrying out of the carbonation step. Numbers of nonvolatile liquid media or carrying materials are disclosed, mineral oils generally being preferred where greases are preferred. U.S. Pat. No. 3,816,310 also teaches that a light or relatively volatile hydrocarbon solvent, such as, by way of example, n-decane, benzene, toluene, Stoddard solvent or n-hexane, though not a critical ingredient, may be incorporated into the composition constituting the aforementioned ingredients, and, when included, it is preferable that it be employed in proportions, in terms of wt. %, from about 20 to 80% of the total of the calcium sulfonate and nonvolatile carrier present in the composition to be processed. In those instances in which the final composition produced by the process is to be used as a grease, a high percentage of the mixture of nonvolatile carrier and volatile hydrocarbon solvent should be volatile hydrocarbon solvent; whereas, if the final product produced by the process is to be used as a rust- or corrosion-protective coating or film, the nonvolatile carrier may be used alone as the carrier or in admixture with relatively smaller amounts of volatile carrier.
In column 10, lines 36-57, of the aforesaid U.S. Pat. No. 3,861,310, reference is made, generally, to the use of commercial equipment in carrying out the process of said patent and it makes the observation that pressure often develops in the reaction system, and that, if such occurs, the process conditions should be modified by adding the water after the carbonation step. The patent goes on to state that the pressure in commercial equipment results from the height of the liquid and also from the particular equipment used; and that, in the latter case, the vapors must be pushed through a condenser and the liquid in the liquid return line causes a resistance which is overcome by increasing the vapor pressure. The said patent also states that the pressure, in those instances in which it is encountered, causes a change in the final product in that, as the pressure is increased, the viscosity of the final product decreases, which is stated to be due to a change in the crystalline form of the calcium carbonate which is formed in the process, the desired form being calcite and the undesirable form being vaterite; that, as the pressure is increased, the amount of vaterite increases and the viscosity decreases; that this can be offset by adding the water after carbonation but below about 70.degree. C. (158.degree. F.), preferably below about 66.degree. C. (150.8.degree. F.); and that, if the water is added above about 70.degree. C., again, more vaterite forms and the resulting lesser amount of calcite causes a decrease in viscosity. In that aspect of the process, generally described in EXAMPLE 13, column 20, and extending through columns 21 and 22 in regard to EXAMPLES 14 and 15; and in column 23, beginning at about line 28, and extending over through line 5 of column 24, wherein, after the carbonation has been completed, water is added to reduce the formation of vaterite. The carbonation is stated to be conducted over a period of 2 hours in EXAMPLE 13 at a temperature maintained in the range of 23.degree.-36.5.degree. C. (72.4.degree.-97.7.degree. F.), and, after cooling at specified cooling temperatures, the water is added over a period of 10 minutes. EXAMPLE 16 of said patent is an Example which is similar to EXAMPLE 15, and EXAMPLE 17 is an Example which is similar to EXAMPLE 16 (apart from the matter of the temperature of the water which is added after the completion of the carbonation), with the exception that EXAMPLES 16 and 17 are stated to have been conducted "under a slight pressure". U.S. Pat. No. 3,816,310 fails to disclose what particular slight pressure or pressures is or are reached in those instances in which, in carrying out the process of said patent, pressure increase may be encountered. It should, further, not go unnoticed that in said aforesaid EXAMPLES 13-17 of said patent, the amounts of methanol are inordinately greater than the small proportions thereof used in our invention as a promoter. In this same vein, it may be noted that even in the case of U.S. Pat. No. 4,579,880 (EXAMPLES 6-13), the carbonation times generally ranged from about 1 to 2 hours and failed to produce a thickened composition in 50 minutes but did in 60 minutes. Finally, again adverting to U.S. Pat. No. 3,816,310, it is recognized, for instance, that EXAMPLES 3, 6, 9 and 12 disclose carbonation times of about 15 to 20 or somewhat less minutes in the non-pressurized carbonation step of said processes, but the overall process times (prior to carbonation) for particular mixing operations or preparation times and the overall process time (excluding subsequent times as are involved in the removal of promoters and volatile hydrocarbon solvents) far exceeded the pressure-carbonation time of the premixed composition and involved an overall different process from the particular 1-step process of our invention.
The foregoing statements in U.S. Pat. No. 3,816,310, particularly that, as the pressure is increased, the viscosity of the final product decreases, which statements, apart from what has been found by us are incorrect at least as far as our present invention is concerned, are irrelevant to our particular present invention, and are devoid of any teaching or any suggestion of our present invention, as will be clear in light of the description of our present invention which is set out in detail below. The concept of the deliberate utilization of predetermined pressures at which the carbonation is conducted, particularly when utilized under controlled temperature conditions and for predetermined relatively short periods of time, when our invention is practiced, with the wholly heretofore unknown and unsuspected significant and dramatic advantages achieved by the practice of our invention, finds no counterpart in U.S. Pat. No. 3,816,310, and was totally unknown to and never envisaged by the patentee of said patent, and in no way, in our considered judgment, even remotely suggests our present invention.
It has also heretofore been known, as shown by U.S. Pat. Nos. 4,505,830 and 4,659,488, to prepare certain metal working lubricant compositions containing a major amount of a lubricating oil, generally a mineral oil, minor amounts of sulfonic acids susceptible to overbasing, lower aliphatic alcohols, oil-soluble carboxylic acids, and sulfur or active-sulfur-containing compounds. As a part of the procedure for the preparation of such compositions, a mixture containing, for example, a sulfonic acid such as an alkylbenzene sulfonic acid, sodium hydroxide or calcium hydroxide, and methanol is prepared which is blown with carbon dioxide gas. It is stated in both of these patents in column 8 thereof (lines 41-46 of U.S. Pat. No. 4,505,830) and lines 61-66 of U.S. Pat. No. 4,659,488) that the reaction or reactions involved are ordinarily carried out at atmosoheric pressure, although superatmospheric pressure often expedites said reaction or reactions and promotes optimum utilization of the reagent identified as B-1, and that the process can also be carried out at reduced pressure but, for obvious practical reasons, this is rarely done. These patents are irrelevant to our present invention in that they are directed to the production of compositions which are not thixotropic overbased calcium sulfonate complex thickened compositions; they do not disclose nor remotely suggest a 1-step process for the production of said thixotropic overbased calcium sulfonate complex thickened compositions; and, indeed, they lead away therefrom because, apart from other considerations, the compositions of said patents must be readily free-flowing non-Newtonian liquids to be effective for the intended purposes of said patents and are antithetical to the thixotropic overbased calcium sulfonate complex thickened compositions of our present invention which are generally in the form of greases or gels or pastes; and, finally, no superatmospheric pressures whatever are indicated in either of said patents. In short, said patents are irrelevant to and could not lead to even the remotest suggestion of our present invention and the improvements and advantages thereof.